Hand cleaning tablet



Patented July 10, 1951 I UNlTElDYSTATES PATENT Y I 2,560,615?

HAND CLEANING TABLET Cherry L. Emerson, Jr., Newton Highlands, andWilliam R. Cuming, Boston, Mass., vassignors to Lawrie L. Witter, astrustee No Drawing. Application January 25, 1949, Serial No. 72,756

, 2 Claims. (01. 252 -89) efiective in cleaning the hands throughattrition and emulsification, Will have sufficient strength includingsmall pellets or bars of soap, have been heretofore known but these havenot been satisfactory products. Further, we are aware that tablets,primarily in the pharmaceutical field,

have been adapted to disintegrate rapidly in:

water, but the techniques used are not feasible in producing a rapidlydisintegrable hand cleaning tablet.

Small bars or pellets of soap or non-soap detergents are notsatisfactory for individual use because in the normal manufacturingprocess the product is so dense that the surface exposed to water foreffecting solution of the detergent is small, necessitating prolongedrubbing by the user. Penetration of water intothe interior of the bar isnegligible. During the rubbing the bar is likely to slip from the handsof the user and become lost; moreover, the central portion of the bar iswasted should the user be able to extract suflicient detergent for hishand cleaning requirements. To decrease the density of the bar to thepoint where rapid disintegration in use occurs is impractical as theproduct then becomes too fragile prior to use.

In tableting pharmaceutical products the technique used for effectingrapid disintegration consists of compressing in a mold a granulation towhich has been added a small quantity (3 to 5% by weight) of dry starchor similar substance. Upon contact with water the starch swells,breaking apart the tablet granules. Effervescence is also occasionallyemployed, the escaping gas serving the disintegrating function. Tomaintain the integrity of pharmaceutical tablets when in the .possiblefor reasons which will presently become clear. 7

In fabricating a rapidly disintegrating hand cleaning tablet thetechniques employed in the tableting art are not applicable. Thedetergents which we have found suitable with regard to their cleaningand emulsifying properties are of a plastic nature, that is, theyundergo considerable plastic flow when subjected to the pressuresnormally used byus in the process of our invention.

Moisture content increases the degree of plastic flow duringcompression. We normally use a granulation which contains approximately2% moisture. Typical satisfactory detergents used by us are alkyl arylsodium sulphonates, and cocoanut oil soap.

To produce an efiective hand cleaning tablet it is necessary that asignificant portion of the composition be a detergent which aspreviously indicated is of a plastic (fiowable under pressure) nature.To produce a hand cleaningtablet in which the active detergentingredient is less than approximately 10% of the tablet weight, theremainder being a pressure non-flowable and water insoluble filler, isfeasible by utilizing established pharmaceutical tableting methods aspreviously outlined. Such a tablet however is impractical since theactive ingredient is diluted to such a degree that the tablet iscumbersome and ineffective We have invented a new and improved one-usehand cleaning tablet and the method of making same in which theproportions of active detergent may be as high as of the weight of thetablet while still maintaining the desirable properties of dry integrityand rapid disintegration in use. The actual percentage of detergentwhich we use depends primarily upon its activity as a cleaning agent. Ingeneral, the non-soap detergents are used in smaller proportions thansoap. We have used soap and non-soap detergents together in severalformulations; In preparing a granulation for tableting, we may eithermix together the tablet ingredients in the dry state or in the presenceof water. In the latter case the material must be dried prior totableting.

The following is a preferred composition. The ingredients as listed willproduce approximately grams of dry composition:

25 grams sawdust 25 grams alkyl aryl sodium sulphonate 50 grams sodiumsulfate 0.8 cc. 1% methylene blue solution 1.0 cc. ortho cresol in amixture of 5 cc. ethyl alcohol and 5 cc. water The alkyl aryl sodiumsulphonate and the sodium sulfate are dissolved in 250 cc. of water andthe solution is brought to a boil. The methylene When the solution isclear blue is then added. the sawdust is added and boiling is continuedto drive oii a part of the water and leave the material in the form of athick slurry. This is placed dome faced plungers.

3 V in a helby m drying p enma t nc a a temperature of 110 C. Thematerial is stirred from time to time to prevent caking and theformation of a detergent film on the surface. When the material is dryit is wetted with the ortho oresol solution and again dried- Thematerial is then broken up, and passed Qtlirough a 10 mesh per inchsieve. The moisture "cd ntefit of the material is brought toapproximately 2% by spraying with water and mixing thoroughly. Thegranulation is then ready for tabletin'g.

Approximately 1.3 grams of material is introduced to a die which is indiameter with V The granulation is compressed to 6,500 pounds per squareinch. The resulting tablets have a void volume to solid constituentvolume ratio of roughly 0.5. These tablets have excellent dry strength,disintegrate readily in use and are extremely effective as hand cleaningagents. 7

We have used a variety of detergents as the active ingredient in thehand cleaning tablet of our invention. Specifically, the followingdetergents have been used and are illustrative:

The alkali salts'of palmitio, stearic, oleic and linoleic acid. Thesesoaps are present in the wool soap manufactured by Swift & Co.

ponol M E Dry.

An alkyl arylsodium sulphonate manufactured by Monsanto Chemical Co. andsold as Santomerse D.

An alkyl sodium'sulphonate manufactured by Dupont and sold as M P I89.Sodium sulfate is incorporated in this product as a diluent. V

A sulphonated glyceride ester manufactured by Colgate Palmolive Peet C0.and sold as Arctic Syntex M. V

A protein'derived detergent manufactured by Kalide Corp. and sold asLamepon 4C.

Obviously other detergents, for example sulfated or sulfonated amides,sulfated or sulforated amines and quaternary ammonium compounds maybeincorporated in the hand cleaning tablet of our invention to achievedesired characteristics.

coalesces into a homogeneous mass when sub'- jected to a pressure of6,000 pounds per'square inch and as non-pressure flowable a materialwhich does not coalesce into or resemble a homogeneous mass whensubjected to a pressure of 12,000 pounds per square inch.

As fillers we have used organic and inorganic materials and combinationsthereof.

The organic materials used include maple wood sawdust, pine woodsawdust, wood flour,

arrowroot starch, corn meal, wheat hulls, ground leather, comminutedpaper, cane sugar and sorbitol. Inorganic materialsv include silica gel,alumina gel, sand, pumice, kieselguhr, sodium carbonate, sodium sulfateand trisodium pliosphate. for imparting specific features to the finalprod- Obviously, other materials may be used uct. For example, sodiumsilicate may be used as a water softening agent.

We prefer to use as a filler a porous hydrophilic solid with a waterpermeable structure of the ultimate particle. Among the organic fillers,those high in cellulose and/or starch content have particular merit. Wehave found the following to be highly satisfactory: wood sawdust, weedflour, cornmeal, silica gel and alumina gel. Sodium sulfate is apreferred non-porous filler when using sulfated or sulphonateddetergents as it is often incorporated as a diluent in commerciallyavailable products.

The particle size distribution of the filler is selected inaccordancewiththe degree of attrition desired in the final product. Wehave found that wood sawdustof screen analysis through 40 and on 48 meshper inch is satisfactory when mild scrubbing is desired. If gentleaction is desired a more finely divided filler is used.

We have discovered the tablet structural conditions which must befulfilled in order to produce'satisfactory hand cleaning tabletsin'which the percentage of detergent constituent i's'high. We have alsodiscovered the mathematical expression which relates the percentageplastic constituent in the granulation to the maximum permissiblepressure to which the granulation may be subjected in the tabletingoperation. Higher pressures than those given by'tlie expression willproduce tablets which "are ii'iisatisfactory as regards wetdisintegration in use.

The expression is:

Pmax=35,0006" where- Pmm=the maximum permissible compression pressure inpounds per squareinch'to produce a satisfactory hand cleaning tablet.

D=the fraction by weight of plastic constituent in the tablet. Theplastic constituent is normally a detergent. h

e is the base of the natural logarithms and has the value 2.72.

I We prefer to produce tablets ,in. whichthe amount of detergent isroughly 0.35'of the tablet weight. We find. that the expression heldslexceedingly well over the range of plastic constituent fractions from0.125 to 0.75. Tablets containing less than 0.125 detergent areineffective hand cleaners, while those containing morethan 0.75detergent have the undesirable"characteristics of a solid bar or pellet.v

In developing the mathematical expressio'n'referred to a large number of"tablets were produced from granulations coh'tainingjvarious percentagesof plastic constituent. The granulations were preparedby'eitlier mixingtogether the ingredients in finelydivided dry form or by preparing awater slurry of the "constituents,

graph paper. Compression pressures which are greater than those given bythe equation yield tablets which do not disintegrate readily. The

equation holds over the range from 0.125 to 0.75

detergent. Below 0.125 plasticconstituent tablets of a hand cleaningtablet which must be realized so that the tablet will have the desirableproperties of dry strength and rapid wet disintegration. We havediscovered that the voids within the tablet must bear a definiterelationship to the volume. occupied by solid constituents. We havediscovered that the void volume to solid constituent volume ratio cannotbe below 0.12 nor greater than 1.8. We prefer to use in our tablets aratio of roughly 0.5. By void volume we mean that volume of a tabletprior to use not occupied by a solid or liquid constituent. Normally thevoids are filled with air which is quickly displaced by water and causesrapid disintegration when the tablet is used.

Experimental data was obtained by preparing a number of granulations andtablets therefrom. The tablets were compressed at various pressures.Flat faced plungers were used in the die. The dimensions of each tabletwere measured; and each tablet was weighed. The total volume of thetablet was obtained by calculation. Tablets for each pressure used weresubjected to dry strength tests and.wet disintegration tests in use. Inthese two respects tablets were rated as excellent, good, poor andunsatisfactory. It is to be noted that a tablet rated as unsatisfactoryin either respect is not suitable as a hand cleaning tablet. Tabletsdesignated at unsatisfactory as regards wet disintegration were, ingeneral, produced at pressures higher than those given by the previouslyreferred to mathematical expression, whereas those rated excellent, goodand poor were produced at pressures below that given by the expression.

The determination of voids was accomplished in the following manner.Dependent upon the materials used in a specific tablet composition, alow viscosity liquid was selected in which all constituents weresparingly soluble. For example, it was determined that tabletscontaining only maple sawdust and Santomerse D, an

alkyl aryl sodium sulfonate detergent manufactured by Monsanto ChemicalCo., were sparingly soluble in acetone. Prior to use the selected liquidwas saturated with the constituents of the tablet. This was accomplishedby allowing a large quantity of the constituents to stand in the liquidfor several days with occasional stirring. Tablets of each granulationand of each pressure used were then immersed in the selected saturatedliquid as prepared above. The liquid was contained in a graduatedcylinder. The change in the liquid level in the cylinder then wasinterpreted as the solid constituent volume of the tablets. In the caseof 'very dense tablets several hours were allowed for penetration of theThis accounts for the low percent-;

1 Example 1 Composition 1 part (by weight) -alkyl. aryl sodiumsulphonate 2 parts-sodium sulfate 1 part- -pine sawdust The granulationwas prepared essentially in accord with the previously outlinedprocedure. The particle size distribution in the granulation was through10 and on 60 mesh.

Dry Strength Wet Disintegration Ratio Excellent Excellen DoIIIIIIT'""'"'IIIII Unsatisfactory I: Poor Excellent--. Unsatisfactory do Example 2Composition:

2 partsalkyl aryl sodium sulphonate 4 partssodium sulphate 3parts-calcium carbonate The granulation was prepared in accord with theoutlined procedure. The particle size distribution was through 10 mesh(0.065 screen opening) and on60 mesh."

Dry Strength Wet Disintegration Ratio Excellent Good o. 433 DoUnsatisfactory. 0.118 Poor- Excellen 0. 748 Unsatisfactory. do 1. 87

Example 3 Composition:

2 parts-alkyl aryl sodium sulphonate 4 parts-sodium sulfate 3parts-silica gel The granulation was prepared in accord with theoutlined procedure. The particles in the granulation passed through a 10mesh sieve.

Dry Strength Wet Disintegration Ratio Good 0.550 Poor 0.204

Example 4 The granulation was prepared in accord with the outlinedprocedure. The particles in the granulation passed through 10 meshscreening.

Dry Strength Wet Disintegration Ratio Excellent Excellent l. 0. 657

Having-thus disclosed our inventionfand described indetailcillustrativeembodimentst'themof; we. claim as new and desiretovsecure by Letters Patent:

1; A'dry'one-use cleaning tablet having adny strength sufficient tosustain it, against breakage in transit and storage, and a void content.sufficient to cause it readily to absorb. water and rapidly disintegratein the presence of: moisture, consisting essentially of a solid ionic.organic detergent and a substantially water insoluble solids fillermixed together and compressed at a pressure of about that given by theexpression R=3;5;0o0er in which D is-the weightv fraction of detergentin the tablet and e ish-thebase-of the 15 natural logarithms and has thevalueof- 2.72, the detergent being not,1ess'than0.125 and not greaterthan 0.75 of the tablet Weight and the 'tablet having a gas void volumeto solid volume in a ratio o f' notless than 0.24 and-snotgreater I 20in whichthe weight ,1 of the detergent-is-bet-ween .25: and: .5 0 of theweight of. the tablet and the filler comprises a granular cellulose.

CHERRY L. EMERSON, JR; WILLIAM R. CUMING;

REFERENCES CITED The following references are of record in the m fileof..tl1is patent:

UNITED STATES. PATENTS Number Name Date 2175,28'5v Duncan Oct. 10, 19392.401647" Bodman Sept; 1'7, 1946 2322 128 Percy June. 10, 1947 FOREIGNPATENTS Number Name Date" 5,698 Great Britain 1881 OTI-IEI-K. REFERENCESPublication: U; S. Dept. of Commerce, National Bureauof StandardsCircular C424--Washing, Cleaning I and' Polishing 'Materials, p. a 17.

1. A DRY ONE-USE CLEANING TABLET HAVING A DRY STRENGTH SUFFICIENT OTSUSTAIN IT AGAINST BREAKAGE IN TRANSIT AND STORAGE AND A VOID CONTENTSUFFICIENT TO CAUSE IT READILY TO ABSORB WATER AND RAPIDLY DISINTEGRATEIN THE PRESENCE OF MOISTURE, CONSISTING ESSENTIALLY OF A SOLID IONICORGANIC DETERGENT AND A SUBSTANTIALLY WATER INSOLUBLE SOLIDS FILLERMIXED TOGETHER AND COMPRESSED AT A PRESSURE OF ABOUT THAT GIVEN BY THEEXPRESSION P=35,000E-2D IN WHICH D IS THE WEIGHT FRACTION OF DETERGENTIN THE TABLET AND E IS THE BASE OF THE NATURAL LOGARITHMS AND HAS THEVALUE OF 2.72, THE DETERGENT BEING NOT LESS THAN 0.125 AND NOT GREATERTHAN 0.75 OF THE TABLE WEIGHT AND THE TABLET HAVING A GAS VOID VOLUME TOSOLID VOLUME IN A RATIO OF NOT LESS THAN 0.24 AND NOT GREATER THAN 0.76,THE TABLET BEING READILY CRUSHED AND DISINTEGRATED IN THE PALM OF A HANDWHEN BROUGH INTO CONTACT WITH WATER.